Abstract: Method of cryptography in a smart card comprising a central processing unit, said method implementing precomputation operations, characterized in that said precomputation operations are performed by the smart card and in that the precomputation operations are carried out at a session during the waiting periods of the inputs/outputs of the central processing unit.

Abstract: The present invention relates to a method of protecting an electronic chip (1) of a user against fraud in transactions between an application (2) and the electronic chip (1).

Abstract: The present invention relates to a cryptographic method of protection against fraud in transactions between an application (1) and an electronic chip (2) of a user.

Abstract: A secured system of access checking using a portable storage carrier (C) on which there is recorded an electronic key (CL), a digital data processing instrument (LE) for the production of keys, and an electronic lock (L) function capable of authorizing access should the storage carrier have the requisite electronic key. To transfer an entitlement to produce keys (CL) from one production digital data processing instrument (LE) to another, it is loaded with a new public key (K′) and the signature (CER′) of this key.

Abstract: A method for performing electronic transactions between a card, a service provider having at least one terminal configured to accept the card and a centralized system configured to be connected to the terminal. The terminal transmits to the card a parameter M including the sum of the transaction and its identity. The card produces two signatures, a first signature (z) depending on a secret debit key (k) and on the parameter (M), this first signature being a proof that the card balance has been debited; and a second signature (y) depending on the first signature (z), the second signature being produced either by an RSA algorithm or by an interactive algorithm. The terminal checks the second signature (y) but not the first one because it is unable to recover the secret debit key (k). The terminal stores the different first signatures (proofs) (z) and the parameters (M) for the different transactions. The centralized system can collect the first signatures and the parameters.

Abstract: The invention relates to systems for checking access limited to authorized time slots renewable by means of a portable storage device.The system comprises, for this purpose, an element (LE) producing electronic keys formed by a data element pertaining to a time slot and by the signature of this data element. These keys are loaded into devices such as memory cards (C). Electronic locks (L) capable of verifying the signatures are implanted in the different (physical or logical) locations, the access to which has to be guarded.Application to the checking of access to buildings or computer systems.

Abstract: A system for interconneting local networks via a public transmission network, in which equipment items of the microcomputer type, connected to a local network A, are capable of being connected to the public network by a router X in order to communicate with one or more equipment items of the microcomputer type connected to at least one other local network B, which are capable of being linked to the public network by a router Y.The system includes security protection of the establishment of the communications between the local networks over the public network, implementing a certificate exchange mechanism and the software procedures for active authentication, of the "challenge-response" type being placed in the routers.

Abstract: Device and process for securing the transmission of telecopies or faxes and a secured telecopier or fax unit having such a security device. The device incorporating a user interface (16) permitting the establishment of a dialogue therewith and a security module (17) permitting the production and checking of digital signatures and preventing replay. The invention also relates to a fax unit including such a device and to a process for securing the transmission of faxes.

Abstract: A binary encoding method notably but not exclusively for the encoding of data elements designed to be represented sequentially, according to a preestablished order, for example in counters, inducing a uniform or substantially uniform mean changing rate for each of the binary elements, the data elements being encoded on two distinct fields of binary elements, a reference field and a permutation field, and the sequence of binary elements assigned to the permutation field undergoing a permutation as a function of the value contained in the reference field.

Abstract: The invention concerns a microcircuit card of the kind comprising:a communication interface;an internal memorypa wired processor unit allowing this internal memory to be addressed from the outside.According to the main characteristic of the invention, provision is made for a secret internal memory zone not addressable from the outside, and the processor unit comprises a wired circuit capable of using the contents of the secret memory for establishing a first serial cryptographic function of two operands and means reacting to the interrogation of predetermined addresses of the internal memory, accompanied by a keyword by applying this keyword and the output of the internal memory as operands of the wired circuit, whilst the output of the wired circuit is applied to the interface.